After that date, most of Ireland left the United Kingdom to become the independent Irish Free State; the remaining part, Northern Ireland, elected to remain in the United Kingdom. Both the Free State and the United Kingdom, which changed its name to the United Kingdom of Great Britain and Northern Ireland in 1927, had the same person as monarch: George V. In 1937, the year after George V's death, the Free State adopted a new constitution which changed the state's name to Ireland (or Éire) and removed all mention of the monarch. In April 1949, Ireland was declared a republic, with the description of the Republic of Ireland. Since April 1949, the only part of the island of Ireland that retains a monarchical system is Northern Ireland (as part of the United Kingdom of Great Britain and Northern Ireland).

Gaelic Ireland consisted of as few as five and as many as nine Primary kingdoms (Cuaighe) which were often subdivided into many minor smaller kingdoms (Tutha). The primary kingdoms were Connacht, Ailech, Airgíalla, Ulster, Mide, Leinster, Osraige, Munster and Thomond. Until the end of Gaelic Ireland they continued to fluctuate, expand and contract in size, as well as dissolving entirely or being amalgamated into new entities. The role of High King of Ireland was primarily titular and rarely (if ever) absolute. Gaelic Ireland was not ruled as a unitary state.

The names of Connacht, Ulster, Leinster and Munster are still in use, now applied to the four modern provinces of Ireland. The following is a list of the main Irish kingdoms and their kings.

Maire Herbert has noted that "Annal evidence from the late eighth century in Ireland suggests that the larger provincial kingships were already accruing power at the expense of smaller political units. Leading kings appear in public roles at church-state proclamations...and at royal conferences with their peers." (2000, p. 62). Responding to the assumption of the title ri hErenn uile ("king of all Ireland") by Mael Sechlainn I in 862, she furthermore states that

the ninth-century assumption of the title of "ri Erenn" was a first step towards the definition of a national kingship and a territorially-based Irish realm. Yet change only gained ground after the stranglehold of Uí Néill power-structures was broken in the eleventh century. ...The renaming of a kingship ... engendered a new self-perception which shaped the future definition of a kingdom and of its subjects.

(Herbert, 2000, p. 72)

Nevertheless, the achievements of Mael Sechlainn and his successors were purely personal, and open to destruction upon their deaths. Between 846–1022, and again from 1042–1166, kings from the leading Irish kingdoms made greater attempts to compel the rest of the island's populace to their rule, with varying degrees of success, until the inauguration of Ruaidri Ua Conchobair (Rory O'Connor) in 1166,

Upon the death of Muirchertach Mac Lochlainn in early 1166, Ruaidhrí, King of Connacht, proceeded to Dublin where he was inaugurated King of Ireland without opposition. He was arguably the first undisputed full king of Ireland. He was also the only Gaelic one, as the events of the Norman invasion of 1169–1171 brought about the destruction of the high-kingship, and the direct involvement of the Kings of England in Irish politics.

One of Ruaidrí's first acts as King was the conquest of Leinster, which resulted in the exile of its king, Dermot MacMurrough. Ruaidrí then obtained terms and hostages from all the notable kings and lords. He then celebrated the Oneach Tailtann, a recognised prerogative of the High Kings, and made a number of notable charitable gifts and donations. However, his caput remained in his home territory in central Connacht (County Galway). Ireland's recognised capital, Dublin, was ruled by Ascall mac Ragnaill, who had submitted to Ruaidri.

Only with the arrival of MacMurrough's Anglo-Norman allies in May 1169 did Ruaidrí's position begin to weaken. A series of disastrous defeats and ill-judged treaties lost him much of Leinster, and encouraged uprisings by rebel lords. By the time of the arrival of Henry II in 1171, Ruaidrí's position as king of Ireland was increasingly untenable.

Ruaidrí at first remained aloof from engagement with King Henry, though many of the lesser kings and lords welcomed his arrival as they wished to see him curb the territorial gains made by his vassals. Through the intercession of Lorcán Ua Tuathail (Laurence O'Toole), the Archbishop of Dublin, Ruaidrí and Henry came to terms with the Treaty of Windsor in 1175. Ruaidrí agreed to recognise Henry as his lord; in return, Ruaidrí was allowed to keep all Ireland as his personal kingdom outside the petty kingdoms of Laigin (Leinster) and Mide as well as the city of Waterford.

Henry was unwilling or unable to enforce the terms of the treaty on his barons in Ireland, who continued to gain territory in Ireland. A low point came in 1177 with a successful raid into the heart of Connacht by a party of Anglo-Normans, led by one of Ruaidrí's sons, Prince Muirchertach. They were expelled, Ruaidhrí ordering the blinding of Muirchertach, but over the next six years his rule was increasingly diminished by internal dynastic conflict and external attacks. Finally, in 1183, he abdicated.

He was twice briefly returned to power in 1185 and 1189, but even within his home kingdom of Connacht he had become politically marginalized. He lived quietly on his estates, and died at the monastery of Cong in 1198 and was buried at Clonmacnoise. With the possible exception of Brian Ua Néill (Brian O'Neill; died 1260), no other Gaelic king was ever again recognised as king or high king of Ireland.

By the time of Ruairi's death in 1198, King Henry II of England had invaded Ireland and given the part of it he controlled to his son John as a Lordship when John was just 10 in 1177. When John succeeded to the English throne in 1199, he remained Lord of Ireland thereby bringing the kingdom of England and the lordship of Ireland into personal union. By the mid-13th century, while the island was nominally ruled by the king of England, from c.1260 the effective area of control began to recede. As various Cambro-Norman noble families died out in the male line, the Gaelic nobility began to reclaim lost territory. Successive English kings did little to stem the tide, instead using Ireland to draw upon men and supplies in the wars in Scotland and France.

By the 1390s the Lordship had effectively shrunk to the Pale with the rest of the island under the control of independent Gaelic-Irish or rebel Cambro-Norman noble families. King Richard II of England made two journeys to Ireland during his reign to rectify the situation; as a direct result of his second visit in 1399 he lost his throne to Henry Bolingbroke. This was the last time that a medieval king of England visited Ireland.

For the duration of the 15th century, royal power in Ireland was weak, the country being dominated by the various clans and dynasties of Gaelic (O'Neill, O'Brien, MacCarthy) or Cambro-Norman (Burke, FitzGerald, Butler) origin. Affairs closer to London ensured, well into the 1530s, that Irish affairs remained at best a secondary concern.

The title of King of Ireland was created after Henry VIII had been excommunicated in 1538, so it was not recognised by European Catholic monarchs. Following the accession of the Catholic Mary I in 1553 and her marriage to Felipe, Prince of Asturias, in 1554, Pope Paul IV issued the papal bull "Ilius" in 1555, recognising them as Queen and King of Ireland together with her heirs and successors.[3]

The Acts of Union 1707 merged the kingdoms of England and Scotland into the Kingdom of Great Britain, under the sovereignty of the British Crown. The effect was to create a personal union between the Crown of Ireland and the British Crown, instead of the English Crown. Later, from 1 January 1801, an additional merger took place between the two Kingdoms. By the terms of the Acts of Union 1800, the Kingdom of Ireland merged with the Kingdom of Great Britain, thus creating the United Kingdom of Great Britain and Ireland. Following the separation of most of Ireland from that kingdom in 1922, the remaining constituent parts were renamed the United Kingdom of Great Britain and Northern Ireland in 1927, five years after the establishment of the Irish Free State.

The King's title in the Irish Free State was exactly the same as it was elsewhere in the British Empire, being from 1922 to 1927: "By the Grace of God, of the United Kingdom of Great Britain and Ireland and of the British Dominions beyond the Seas King, Defender of the Faith, Emperor of India" and, from 1927 to 1937: "By the Grace of God, of Great Britain, Ireland and the British Dominions beyond the Seas King, Defender of the Faith, Emperor of India". The change in the King's title was effected under an Act of the Parliament of the United Kingdom called the Royal and Parliamentary Titles Act, 1927, intended to update the name of the United Kingdom as well as the King's title to reflect the fact that most of the island of Ireland had left the United Kingdom. The Act therefore provided that "Parliament shall hereafter be known as and styled the Parliament of the United Kingdom of Great Britain and Northern Ireland [instead of the Parliament of the United Kingdom of Great Britain and Ireland]" and "In every Act passed and public document issued after the passing of this Act the expression 'United Kingdom' shall, unless the context otherwise requires, mean Great Britain and Northern Ireland."[4]

According to The Times, the "Imperial Conference proposed that, as a result of the establishment of the Irish Free State, the title of the King should be changed to 'George V, by the Grace of God, of Great Britain, Ireland, and the British Dominions beyond the seas King, Defender of the Faith, Emperor of India.'"[4] The change did not mean that the King had now assumed different styles in the different parts of his Empire. That development did not formally occur until 1953, four years after the new Republic of Ireland had left the Commonwealth.

The British monarchy, specifically, continued and continues in Northern Ireland, which remains a part of the sovereign state that is the United Kingdom of Great Britain and Northern Ireland. From 1921 until 1973, the British monarch was officially represented in Northern Ireland by the Governor of Northern Ireland.

The changes in the royal style in the 20th century took into account the emergence of independence for the dominions from the Imperial Parliament of the United Kingdom. The kings successively and their advisers and governments in the United Kingdom were fully aware that the republican intent of the representatives of the Irish Free State was in marked contrast to the intent of the governments of certain other dominions, such as Canada.[12] and such differences were manifested in this period in the design and use of flags and other national symbols for the Irish Free State and other dominions.[13]

^In the words of Mary E. Daly (January 2007). "The Irish Free State/Éire/Republic of Ireland/Ireland: "A Country by Any Other Name"?". Journal of British Studies. 46 (1): 72–90. doi:10.1086/508399. JSTOR10.1086/508399.: "After the enactment of the 1936 External Relations Act and the 1937 Constitution, Ireland's only remaining link with the crown had been the accreditation of diplomats. The president of Ireland was the head of state. When opposition deputies asked de Valera whether Ireland was a republic—a favorite pastime in the mid-1940s—he tended to resort to dictionary definitions showing that Ireland had all the attributes of a republic."

^Kondō, Atsushi (2001). Citizenship in a Global World: Comparing Citizenship Rights for Aliens. Hampshire: Palgrave. p. 120. ISBN0-333-80265-9. Ireland reluctantly remained a member of the Commonwealth as Irish citizens remained British Subjects. However, Irish representatives stopped attending Commonwealth meetings in 1937 and Ireland adopted a position of neutrality in World War II. Ireland became a Republic in 1949 and formally left the Commonwealth.

^Proclamation altering the Style and Titles appertaining to the Crown, London, 13 May 1927.[1]

^Heads of government attending the 1926 Imperial Conference included W. T. Cosgrave, then serving as President of the Executive Council (prime minister) from 1922 to 1932. It was recorded that the distinct characteristics and histories of each was recognised by the parties attending the Conference,

^See "The Flags of Canada", Alistair B. Fraser, 1998, [2] 1_For the chronology of Canadian flags from 1870, at the time of the Irish republican movement, see Appendix III [3]. 2_For explanation of the distinction between national flags and monarchical badges or blazons of arms see Chapter I: ___"...a nation needs emblems and symbols to preserve traditions and inspire love of country. Of these symbols, the coat of arms and the flag are the chief." Charles Frederick Hamilton, Assistant Comptroller, R.C.M.P (1921) ___"The function of a flag is to send the simple message of identity. The function of arms is to dignify an individual, or institution, or country by special identifying symbolism and by appropriate reference to ancestry." John Ross Matheson, Canada's Flag: A Search for a Country (Boston G.K. Hall, 1980), p. 7. ___"Canada's flag serves to identify something Canadian. More specialized in its use, Canada's arms identify national authority and jurisdiction. Leaving aside strictly decorative uses of either, the flag is used wherever one wishes to make the simple statement: Canada or Canadian; the arms only where the authority of the nation is asserted." Alistair B. Fraser, 1998, op.cit.

Kings, the kingship of Leinster and the regnal poems of "laidshenchas Laigen:a reflection of dynastic politics in leinster, 650–1150, Edel Bhreathnach, in Seanchas:Studies in Early and Medieval Irish Archaeology, History and Literature in Honour of Francis John Byrne, Four Courts Press, Dublin, 2000